Functional anomaly mapping reveals local and distant dysfunction caused by brain lesions

The lesion method has been a cornerstone in the endeavor to understand brain-behavior relationships in humans, but has relied on the flawed assumption that anatomically abnormal tissue functions abnormally and anatomically normal tissue functions normally. To address this longstanding problem, we introduce an approach to directly map the degree of functional anomaly throughout the brain in individual patients. These functional anomaly maps identify anatomical lesions and are stable across measurements. Moreover, the maps identify functionally anomalous regions in anatomically normal tissue, providing a direct measure of remote effects of lesions such as diaschisis. Lesion-behavior mapping using these maps replicates classic behavioral localization and identifies relationships between tissue function and behavior distant from the anatomical lesions. This method provides brain-wide maps of the functional effects of focal lesions, which could have wide implications for one of the most important methods in neuroscience.